Insights into ovarian response with a fixed low dose FSH stimulation in an IUI programme: the PRORAILS study

Abstract STUDY QUESTION Are patients’ characteristics, such as anti-Müllerian hormone (AMH) and BMI, reliable factors to predict ovarian response in couples with unexplained subfertility undergoing IUI with ovarian hyperstimulation (IUI-OH)? SUMMARY ANSWER We observed no solid relationship between serum AMH and ovarian response. WHAT IS KNOWN ALREADY Ovarian stimulation during IUI treatment could lead to a higher chance of pregnancy, but also a higher incidence of multiple pregnancies, unless strict cancellation criteria are being used. Several factors could influence the result of the stimulation, such as age, BMI and hormonal status of the female. In IVF treatment, AMH has shown to be a useful predictor of ovarian stimulation to optimize the outcome; however, in a milder stimulation protocol, such as IUI, this has not been investigated. STUDY DESIGN, SIZE, DURATION We performed a prospective cohort study and evaluated the first IUI stimulation cycle of 492 patients. The study was conducted between 2012 and 2017. Follow-up ended if patients were not pregnant after the first cycle. If pregnancy did occur, follow-up lasted until delivery. PARTICIPANTS/MATERIALS, SETTING, METHODS PRORAILS is a large multicentre nationwide cohort study executed in the Netherlands. Eligible women aged 18–43 years who were diagnosed with unexplained subfertility or mild male subfertility according to the Dutch guideline, with a regular indication for IUI-OH, were asked to participate. Ovarian response was assessed using a transvaginal ultrasound 5–7 days after initiation of the stimulation and was repeated according to the size of the leading follicles. Ovarian response was defined as optimal or suboptimal based on the total number of dominant follicles >15 mm. A successful stimulation was defined as the presence of two to three follicles >15 mm on the day of hCG administration. Serum AMH (µg/l) was measured by ELISA, and samples were taken on day 2, 3 or 4 of the menstrual cycle. Poisson regression was used to estimate the risk of a suboptimal ovarian response. MAIN RESULTS AND THE ROLE OF CHANCE Of the 492 participants, the mean age was 33 years and the mean subfertility duration was 2.5 years. The median serum AMH was 2.1 (µg/l). The majority of patients had a suboptimal response: 326 women (66%), of whom 224 (45%) had a hypo response (defined as 15 mm) and 102 (21%) had a hyper response (defined as more than three follicles sized >15 mm). The lowest A